Telegraphy



T. B. DIXON.

TELEGRAPHY.

APPLKIATION FILED JAN. 15. 1920.

Patented Mar. 7, 1922.

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IN VE N TOR UNITED STATES THOMAS BULLITT DIXON, OF BROOKLYN, NEW YORK.

TELEGRAPHY.

Specification of Letters Patent.

Patented Mar. '7, 1922.

Application filed January 15, 1920. Serial No. 351,563.

To all whom it may concern:

Be it known that I, THoMAs BULLITT DIXON, a citizen of the United States of America, and a resident of the borough of Brooklyn, county of Kings, city and State of New York,'have invented new and useful Improvements in Telegraphy, of which the following is a specification.

My invention relates generally to telegraphy, and, particularly, to duplex telegraphy, and, speaking generally, embodies means for obviating certain disadvantages which may arise as the result of placing certain auxiliary devices in the circuit of a cable on Which is employed the duplex method and apparatus of my invention set forth in my application for Letters Patent, Serial No. 199,651, filed November 1, 1917.

According to requirements in different cases in practice, the signal receiving coil of a cable duplex system is sometimes shunted by a non-inductive resistance, or by an inductive resistance, or by a capacity, (either or both of which latter may also have a non-inductive resistance in series therewith), or by a combination of any two of these, or of all three, as the particular case may require, to attain best practical results in shaping signals and eliminating disturbances in general. In the application of my said duplex invention to such conditions, I may sometimes correspondingly shunt the disturbance neutralizing coil thereof with a non-inductive resistance, or with an inductive resistance, or with a capacity, or with any or all of these combined, in order to compensate, as nearly as may be, through modification of the disturbance neutralizing currents, for any distortion of the disturbance currents which may result from the employment of such shunts in connection with the signal receiving coil.

For similar reasons, I may, in cases where desirable, include in the circuit of the disturbance neutralizing coil, in series with the coil, any of the devices commonly employed for shaping the signals and placed in the cross-wire of a cable duplex in series with the signalling coil, such as non-inductive resistance, inductive resistance, capacity, or any or all of these 1n the various relationships to each other of shunt and series in which they are ordinarily em-' ployed.

In general, I may employ any auxiliary deviceor devices in the circuit of the disturbance neutralizing coil (or coils) which are employed in the circuit of the signalling coil, in order to compensate for distortions of the disturbance currents which may result from the employment of such devices in the circuit of the signalling coil.

The accompanying drawing, typifying a structure or system 111 which the present in-- justable non-inductive reslstance 6 and wire 5 to the usual quarter ohm adjustable resistance 7, which connects with wire 8 leading through the usual block condenser 9 to the cable 10 and with wire 11 leadingthrough the companion block condenser 9 to the artificial line 12, connected to earth at 13. 14 is the usual signalling coil of the home receiving instrument, and attached rigidly to it is a disturbance neutralizing coil 15, both coils being suspended between pole pieces 16 of a suitable magnet. The coil 14 is connected in the usual way in the cross-wire of the bridge, which also includes the usual receiving condenser 17 having an adjustable resistance 18 in series therewith both condenser and resistance being shunted by an adjustable resistance 19. The coil 14 has in series with it an ad'ustable resistance 20, and the coil is shunte by an ad'ustable resistance 21, and a capacity 22, w ile the coil, resistance and capacity are shunted by an adjustable resistance 23. All the devices in the cross-wire are shunted by an inductive shunt 24, having in series with it an adjustable resistance 25. The coil 15 has its terminals connected to a. pole changing switch to the le or to the right. Handle 27 supports blades 28, which connect with wires 29, as shown, in such manner that when the which it will flow when the handle 27 is thrown over and points to the right, such pole-changing switches being well-known. Disturbance neutralizing coil 15 has in circuit with it devices corresponding with those in circuit with coil 14, comprisin a condenser 17, having an adjustable resistance 18 in series therewith, both condenser and resistance being shunted by an adjustable resistance 19'. with it an adjustable resistance 20, and the coil is shunted by an adjustable resistance 21 and a capacity 22', while the coil, resistance and capacity are shunted by an adjustable resistance 23'. All the devices in circuit with coil 15 are shunted by an inductive shunt 24' having in series with it an adjustable resistance 25'. Let it be assumed that there is an imperfect balance between cable 10 and artificial line 12 so that when either of the transmitting keys 1 1 is operated, outgoing current flows through the cross-wire C and signalling coil 14 so as to cause a false movement of the coil 14. Under these conditions resistance 6 is adjusted to a value just sufficient to send enough current through coil '15 to neutralize the effect of the current flowing through coil 14, the switch 26 being set so that the current flowing through coil 15 is of proper direction for this purpose. Assuming the winding of coil 15 to exactly equal that of coil 14in number of turns and size of wire, so that its self-induction will equal that of coil 14, or that where the winding of the coils is unequal, the self induction of the two coils is made equal by suitable means, such, for example, as that set forth in my said application, no time factor error will result from unequal self-induction of coils 14 and 15. It will be seen that the currents through coil 14 caused by imperfect balance will be neutralized since, with proper adjustment of resistance 6, the opposing currents caused to flow through'coil 15, which are a small fraction of the sum of the outgoing currents flowing into the main and artificiallines and of-the discharge currents therefrom will have time and energy factors corresponding substantially to that of the currents flowing through coil 14. To the extent that the condenser17, resistances 18, 19, 20, 21 and 23, capacity 22, inductive resistance 24 and resistance 25 act to distort the disturbance currents flowing through coil 14, similarly the corresponding devices, condenser 17, resistances 18, 19', 20, 21' and 23', capacity 22', inductive reslstance 24' and resistance 25 will act to Coil 15 has in seriesdistort the disturbance neutralizing currents so that their function in neutralizing the effects of the disturbance currents on the signalling coil 14 will not be interfered with. The exact arrangements here illustrated may be varied according to requirements of practice, and it would not be feasible to show all the variations of circuit conditions likely to arise in practice, but the illustrations given will enable any one skilled in the art to apply this invention to meet any conditions that may' arise. Its application to the several figures of my said application for Letters Patent will be obvious, and, accordingly, need not be particularly illustrated and described. 1

What I claim is:

1. In a system of duplex telegraphy, of the general class described, embodying main and artificial lines and disturbance neutralizing means influencing the signal receiving means in such manner that the effects of disturbance currents due to imperfect balance between the main and artificial lines are neu-. tralized by said disturbance neutralizing means, the herein described method of compensating for the effects of distortions of the disturbancecurrents resulting only from the auxiliary devices employed in connection with the signal receiving means, which consists in distorting the disturbance neutralizing currents to correspond with the distor tions of said disturbance'currents.

2. In a. system of duplex telegraphy, of the general class described, embodying main and artificial lines, and disturbance neutralizing means influencing the signal receiving means in such manner that the effects on the signal receiving means of imperfect balance between the main and artificial lines are neutralized by said disturbance neutralizing means, auxiliary devices in combination with the signal receiving means for shaping the signals and eliminating disturbances in general, and means associated with the disturbance neutralizing means for distorting the disturbance neutralizing currents produced by the disturbance neutralizing means, whereby the distortion of the disturbance neutralizing currents is made to correspond with the distortions of the disturbance currents caused only by said auxiliary devices employed in connection with the signal receiving means.

3. In a system of duplex telegraphy, in combination, a main line, an artificial line,

a signal receiving instrument in the crosswire of the bridge formed by the said main and artificial lines, auxiliary means associated with said signal receiving instrument which distort the disturbance currents flowing through said in'strument,as a result of imperfect balance between the main and artificial lines, disturbance neutralizing means influencing the signal receiving means for neutralizing the effects of said disturbance In testimony whereof I have signed this currents, and means associated with said specification in the presence of two subscrib- 10 disturbance neutralizing means for distorting witnesses.

ing the neutralizing currents, whereby the distortions of the neutralizing currents are THOMAS BULLITT'DIXON' made to correspond to the distortions of the Wltnesses: disturbance currents caused only by said DOROTHY E. HALPERIN,

auxiliary means. 7 JAMES H. 131mm. 

